"They are presumably the most ancient soil dwellers and have been around in sediments of the Precambrian and Ordovician [over 500 million years ago]," he says.

Byzov and his colleagues dug up worms from soils rich in cow manure, then measured the amount of bacteria and fungi in soil and "fresh excrement" from worms.

Interestingly, the worm poo contained a different microorganism mixture, with significantly fewer fungi.

The scientists then took fluid from the worms' digestive tract and subjected it to a bacterial and fungi barrage.

Filters, ferments

The tests indicate the earthworm gut filters, and even ferments, at least some types of microorganisms.

"Earthworms selectively kill and then digest some bacteria and fungi," says Byzov. "Other microorganisms can successfully pass the digestive tract with some populations multiplying in the posterior part of the gut."

He says this activity helps to keep soil microbial communities in balance. Worm poo even changes how soil absorbs water.

"[Earthworms] make soil more water resistant through their excretion of mucus-rich casts," Byzov says.

"Consuming soil, they make big channels and burrows, which are then easily occupied by plant roots and small animals."

Chinese worms kill too

As these experiments were taking place, Sun Zhenjun from China Agricultural University in Beijing and colleagues were making worm discoveries of their own.

Zhenjun knew that, for centuries, traditional Chinese medicine practitioners had included worms in their preparations.

He describes the insect treatments as "cold" and "slightly salty", with claims of treating everything from herpes to cancer.

The Beijing team introduced cancerous cells, obtained from China-Japan Friendship Hospital, to worm tissues and fluids.

The researchers say they saw significant change, with many of the cancer cells dying.

Carbohydrates and proteins

Zhenjun says he and his colleagues then accidentally found that worm compounds, specifically some complex carbohydrates and protein components, have antibacterial functions.

Like Byzov, Zhenjun's team mix all kinds of human-infecting microbes with the worm compounds, such as Escherichia coli, staphylococcus, pneumonia-causing bugs and candida.

The worm goo easily killed off each one, including the extremely harmful bacteria Pseudomonas aeruginosa, which is naturally resistant to penicillin and most other antibiotics.

Zhenjun and his colleagues are now trying to isolate the most powerful anticancer and antibacterial agents in worms, so that these might be synthesised for human use in future.